The present plasma transfusion recommendations were largely based on studies of plasma exchange patients and the use of data from the 1970's. In plasma exchange, patients have a controlled removal of their plasma that is ultimately replaced with donor plasma. Coagulopathy develops solely from the amount of plasma removal since no consumption of factors exists. Hemorrhaging patients however lose coagulation factors both in shed blood and due to ongoing consumption at sites of injury. Further, the hemodynamic instability and hypovolemia experienced by hemorrhaging patients further exacerbates the reduction in clotting factor levels. Prior to the late 1980's, hemorrhaging patients often received whole blood transfusions. Whole blood, no longer used in most circumstances, contains approximately 1 unit of plasma in each unit. Thus, patients receiving whole blood will not develop a coagulopathy as quickly as patients who receive the now standard packed red blood cell units.